Electrical-etching apparatus.



J. H. WEEKS.

ELECTRICAL ETCHING APPARATUS.

APPLICATION FILED SEPT- H. 1916.

Patented Aug. 20, 1918.

4 SHEETSSHEET 1.

J. H. WEEKS.

ELECTRICAL ETCHING APPARATUS. APPLICATION FILED'SIEPT. 11. 1916.

l ,2? 6 ,600 Patented Aug. 20, 1 918.

4 SHEETSSHEET 2.

J. H. WEEKS.

ELECTRICAL ETCHING APPARATUS.

APPLICATION FILED SEPT. 11. 1916.

1,276,600. Patented Aug. 20, 1918-.

4 SHEETS-SHEET 3- attorney v J. H. WEEKS, ELECTRICAL ETCHING APPARATUS.

APPLICATION FILED SEPT- I, 1916. 1 27 690, Patented Aug. 20, 1918.

4 SHEETS-SHEET 4.

j @0 8., L T

K I i I 66% u I a I I I 5.) 0 7 JOSEPH H. WEEKS,.-OF RUTLEDG-E,PENNSYLVANIA, ASSIGNOR Tb JACKSON S. WEEKS,

OF DELAWARE COUNTY, PENNSYLVANIA, AND RAYMOND M.

PHIA, PENNSYLVANIA, TRUSTEES.

WEEKS, or PHILADEL- revenue.

Specification of Letters Patent. Patented Aug. 20, 1918.

Original application filed J'uly 8, 1916, Seria1 No. 108,232." Dividedand this application filed September 11,

' l 1916. Serial No. 119,548.

To all whom it may concern:

Be it known that l, JosEPH H. WEEKS, a citizen of the United States ofAmerica, residing at Rutledge, in the county of Delaware and State ofPennsylvania, have invented certain new and useful Improvements inElectrical-Etching Apparatus, of'which the following is a specification,reference being had therein to the accompanying drawmg.

The anode or anodes are given an intermittent or periodic motion in theelectrolyte by mechanical means automatically controlled. The cathodesare so located and spaced with respect to the anodes as to produce sharpand clean effects. Means are provided in the form of brushes whichautomatically keep the cathodes clean. Anode and cathode circuitconnections are made very simple, but perfectly balanced to secureequalized distribution of the current. Other features of improvementwill appear from the following detailed description.

This application is a division of my prior application Serial No.108,232, filed July 8, 1916.

Certain forms of apparatus made use of in carrying out my invention areillustrated in the accompanying drawings to which reference willbe hadin the description and in which Figure 1 is a perspective view of theimproved etching tank used in carrying out my invention.

Figure 2 is a continuation of Fig. 1 showing in perspective the drivingmechanism.

Fig. 3 is a perspective view partly in section of the etching tankequipped with mechanically driven brushes for removing sludge fromthecathodes.

Fig. 4 is a detail of the adjustable brush holder.

Fig. 5 is a perspective detail view showing the arrangement of the brushin this holder.

My invention relates to electrical etching Fig. 6 is a detail of thebrush rod adjustment.

Fig. 7 is a detail of the link connection between the brush mechanismand the operating shaft.

Fig. 8 is a plan view of a tank with a plate. suspended therein, facedown, and cathodes hung Vertically upon wires along the sides and endsof the tank.

Fig. 9 is a longitudinal view of the same partly in section, showingcams and slides for raising and lowering the plate in the solution.while etching.

Referring to the drawings, and especially to Figs. 1 and 2, 1 indicatesan etching tank which may be of any suitable waterproof and insulatingmaterial, or otherkind of material rendered waterproof on the inside,such as Wood coated on the inside with an insulating waterproof andchemical resisting material. The usual drain cock 2 is provided for thepurpose of draining the tank when necessary to change the solution orempty for repairs. Positioned within the tank around the four sidesthereof so as-to be immersed and substantially surround the electrolyte,are the cathodes 3 which may be of any suitable conducting material butare preferably of carbon. As it is difficult to obtain and use, witheconomy, carbon plates of the dimensions and proportions desired, I findit expedient and advantageous to form these cathodes of a number ofcarbon plates 4 held and protected by a frame 5. Electri cal connectionis made between the cathode plates 4 and a bus 6 by means of a pluralityof flexible conducting members 7 extending in parallel connectionbetween the said cathode, plates and bus bar. This bus bar 6 extendsentirely around the outside of the,

opposite ends of the tank 1 and is prevented from coming in contact withthe flexible connections 7 of the end cathode plates by the insulatingblocks 9.

Each of t iese blocks 9 is provided with transverse channels 10 in itslower surface to accommodate the conductors 7 and carries on its uppersurface a pair of vertical guide rods 11 positioned near the ends of theblocks so as to include the plate support 8 and prevent lateraldisplacement thereof during its up and down movement.

In this up and down movement of the plate support it is desirable thatit be given. a certain cycle of operation which 1 have found makes forbetter results and therefore constitutes an important part of theprocess to which the present invention pertains. The driving andoperating mechanism for producing th movement of the plate supportconsists of a suitable prime mover such as the electric motor 12 mountedabove the tank on the platform 13 supported on suitable wall bracketssuch as The motor 12 is connected through a reducing gear 15 to acountershaft 16 rum ning parallel to the etching tanks, of which theremay be any number, ano carrying at its ends a pair of crank disks 16.Each of these crank disks is connected through a crank pin 1? and link18 to a sliding shaft 19 hearing at its ends in slotted side brackets20, which side brackets are arranged to permit the shaft 19 to move onlyup and down in a vertical plane longitudinal of the tanks. Connection ismade between the shaft 19 and plate support 8 by means of flexibleconnections 21. With this arrangement the comparatively slow rotarymovement of the shaft 16 is transformed into a variable v r ticalmovement of-the sliding shaft 19, due

to the crank and pinion connection between them.

By adjusting the length of the flexible connections 21, I may obtainvarious degrees of lost motion between the plate support 8 and the shaft19, whereby the continuous motion of the shaft'19 may be transformedinto an inte mittent motion of the plate sup port, the cycle of whichmay be varied as re gards the relative periods of rest and movements byadjustment of the length of the flexible connections 21. For example, ifthe fleiiiole connections 21 are so adjusted that when the shaft 19 isat its highest point, the plate support 8 will swing a given distanceabove the insulating blocks 9. this distance will represent the limit ofthe amount of vertical movement given to the plate support 5 and throughit to any plates suspended therefrom in the electrolyte, any furthermovement that would otherwise be transmitted to it from the rod 19 beinglost through the flexible connection when the plate support comes torest on the insulating blocks 9. Thus any plat-es carried by the support8 will remain at rest in the solution during a certain portion of thecycle and be remainder, the extent 0 movement and toe relative durationof th rest and moving periods depending upon the amount of lost motionbetween the shaft 19 and support 8, while the duration of the completecycle would be determined bythe speed at which the driving apparatus isoperated. lt is not desirable to have the plates move all the time,although this may be accomplished by adjusting the flexible connections21 in a manner that will be ob vious. In any case the plates are ofcourse immersed all the time. As a specilic example of an adjustment toproduce a given cycle, if the full stroke of the rod 19 is 11 inches andthe connections 21 are adjusted to raise moved during the r the platesonly 2 inches, the time of motion of the plates will be 2/11 of thewhole cycle, while the period of'rest will be 9/11 of the whole cycle.

During etching, an occasional interruption of the current is desirable,and in fact important, because it tends to keep the face of the anode(the plate being etched) clean, andflassists in producing smoothness ofetching. A plate to be so treated is indicated at 22 which is suspendedfrom the support 8 by a suitable metallic hook 23 through which itreceives current from the conducting support and which hook is soarranged that it may be lifted out of connection with the member 8 tointerrupt the flow of current to the plate 22. This lifting of the hookwith a resulting interruption of the cur r nt flow is effectedperiodically by means of a suitable flexible connection 2% connecting Ithe hook with the sliding rod 19 and so adjusted as to its length thatthe lost motion between the book 23 and the rod 19 will be taken upbefore that of the support 3, thus causing the hook 23 to be raisedslightly in advance of the support 8 and held out of electrical contactwith the support until it again comes to rest on the insulating blocks9, when the connection 21 becomes slack and after that the connection 2permitting the hook 23 to again come to rest on the support 8 inelectrical contact therewith. Thus, in tie case of a plate connected as22, it is not only periodicallv moved up and down in the electrolyte buthas its supply of current periodically cut 01%, the duration of eitherof which conditions may be varied by suitable adjustment of the flexibleconnections 21 and 24 in a manner which will be obvious. it is furtherto be noted that, if desired, the plate 22 may be made to remainstationary during the whole cycle of movement of the rod 19 with only aninterruption of the circuit once in each cycle. This of course could beeffected by slacking the connections 21 sufficiently to allow thesupport 8 to remain stationar at all times.

For supplying curr S and 8.

it to the conductors J. provide a pair of looped bus bars and an evendistribution of the volume ofthe current is essential, the arrangementof certain connections must be such as to avoid any difference in thedrop of potential at the different points of connection. It is to thisend that the connection is made from opposite ends of the support 8through separate conductors 28 and 29 to individual positive bus barmembers 25, and from opposite ends of the continuous bus 6 throughseparate conductors 30 and 31 to separate negative bus bar members 26.Where more than one tank is connected up at a time to the same dynamo,those connected nearest the dynamo to the bus members 25 and 26 will besubjected to a voltage slightly higher than the farther tanks but withthe arrangement of connection shown, this will not affect the evendistribution of current as regards the individual tanks.

Where it is desired to surround the electrolyte on all four sides andbottom with the cathode members, a fifth cathode member is provided,which substantially covers the bottom of the tank and to whichconnection is made to all four edges thereof from the four sides of thebus 6 by means of conducting members such as 32 passing through the sidewalls of the tank through suitable watertight insulating brushes 33, orby in sulated cables over the top of the tank.

When electrolytes are employed which tend to form sludge or a coating onthe cathodes, I provide mechanical means for disengaging the sludge andkeeping the cathodes clean. A preferred form of this means is hereillustrated in Figs. 3 to 7 inclusive, and while for the sake ofclearness I have not shown it combined with the ar- 1 rangement of Figs.1 and 2, it is to be understood, of course, that it is to be used incombination with the former arrangement .of

apparatus, that is in association with a common tank. This cleaningarrangement consists generally of a set of brushes 34 arranged to bemoved up and down across the inner faces of the cathodes by suitablereciprocating mechanism such as the sliding shaft arrangement of Fig. 1preferably identical therewith and which shall be so described. i

Referring more in detail to the structure of the cleaning mechanism, thebrushes 34 i are connected to the side rods of the rectangular frame 35through adjustable connecting devlces 36 each comprising a frame or rodengaging portion the form of a collar and set screw and a brush engagingportion 38 in the form of a C clamp having a pointed anchor stud 39 andclamping screws 40. With this novel form of connection between thebrushes and the frame, the

7 brushes may be set either to cause the edge or the entire face toengage the cathode. To take up wear between the brushes and thecathodes, the rods forming the frame 35 are connected at each of thefour sides through right and left threaded turn buckles 41:

' The brush carrying frame 35 is carried by a pair of forked rods 42 thetines of each fork connecting with the corners at opposite ends of theframe. The arm 43 of each forked rod carries a bifurcated member 44 inwhich is pivotally secured the lower end of a connecting rod 45 having aU-shaped 'head 46 open at the side and adapted to straddle the slidingshaft'19. The space between the arms of the U-shaped head is slightlytaperedtoward the open end so that when the head is slid over the rod 19the open end only will offer an appreciable resistance, the closed endfitting freely around the shaft. To secure connecting rod 46 againstdisengagement from the shaft 19,

a bolt or pin 47 is provided which extends across the open side throughperforations 48 therein.

It will be seen that-the forked members 42 are amply wide enough topermit free operation of the plate support 8 and easy access to thedifferent parts by the operator. When this cathode cleaning mechanism isused, it is preferable to omit the fifthor bottom cathode.

Figs. 8 and 9 show another form and arrangement of a tankandappurtenances for carrying out my process. In these figures,projections 50 on the sides of the tank carry a wire or rod 51'extending around the entire upper part of the tank and having extensionterminals connected to the negative terminal of the source of current.

My cathodes. 52, consisting preferably of carbon rods provided withmetal caps and hooks at their upper ends, are hung from this wire. InFig. 9- twelve ofthese cathodes are swung, but the number is immaterial,so long as their combined surface is greater than the surface of theanode or' late tobe etched.- A liberal allowance in this respect isproductive of good results, The anode or plate is shown at 53, suspendedface down from a pair of rods 54, consistingof copper wire bent in aloop at each end, and connected at both ends to the positive terminal ofthe source of current, which is preferably.

a dynamo of low voltage, but may be any convenient and suitable source.

When a large quantity of solutionis em it very desirable to gently movethe anode constantly recurring intervals as before described for Fig. l.ldechanism for producing this motion of the plate is also provided inthe form of apparatus shown in Figs. 8 and 9. I here show a shaft 55heneath the tank, with its ends journaled in hearings secured theretoprovided with a. pulley 56 at one end for attachment to any suitable criving means. Vertical slides 57 are provided on the ends of the tankwhich at their upper ends carry the wires or rods 5sand at their lowerends are slotted to slide up and down on the shaft, with roller hearings58 resting upon the surface or rotary cams 59 on the shaft. Asthe shaftrotates. the came 59 raise and lower the rollers 58 and the slides 5'?to which they are attimhed thereby raising and lowering the wires whichplay between guides 60 in the top of the tank.

ln order to lessen the quantity of solution required in the tanlz, andalso to draw the heavy solution flowing from the anode plate directly tothe base of the cathode or cathodes, I insert filler or clock shown inFigs. 8 and 9. This is geometrically shaped preferably with triangularends, sloping sides, and its longitudinal ridge lying directly under theanode plate. It is made of acidresistant material or wood or metalcoated with the same and water-tight. This filler is shown at 61, indotted lines in Figs. 8 and 9.

l consider it novel and original with me to arrange the cathodes in themanner shown and described in the several figures so as to permit aneven distribution of the current in all parts of the hath. l havehitherto worked upon the generally accepted theory that the anode andcathode must face each other in parallelismso that the passa e ofcurrent from one to the other through the bath should he in lines asnearly normal to looth surfaces as possible; but experience has shown methat this is unnecessary, provided that the "points of sufficientsurface and even distribution of current are taken care of.

For the solution or electrolyte in the tank. I may employ any one ofanumller of formulas, all well known to thosesltilled in the art. Theregular electrotypers formula so-called, consists of sulfate 01 copperdis solved in water to make a solution testing 10 on the Baumehydrometer, with sufiicient sulfuric acid added to bring the hydrometertest to 15. This may he used, out I prefer certain formulas of my own,which 1 shall now state but shall not claim herein as apart of myinvention, the same being claimed in my prior application of which thisis a division.

Solution No. i: Dissolve calcium chlorid in water until the solutionregisters from 5 (with heavy hydrometer to a point of almost saturation.This solution can he used alone hut preterablyl add an acid which may benitric. hydrochloric, chromic,

citric. or acetic. Other acids may he en1- ployed if desired. Theproportion oi acid as well as the strength or calcium chlorid vary withthe character of the worl: to be done. it is obvious that with thestronger acids a smaller quantity thereof is required; and the strongerthe calcium chlorid solution thelarger the amount acid which may beemployed. These acids increase the conductivity of the solution. whichalso varies with the strength of the chlorid solution. The acids alsoserve to keep the face of the anode clean and bright.

Solution No. 2.: This is made according to the foregoing formulafollowing the same remarks, hut suhst-itutinn' sodium chlorid commonsalt) in place or calcium chlorid.

Elolution Ho. 3: This solution is made in exactly the same way andaccording to the same directions as No. l, but ammonium chlorid(salamoniac) is substituted for the calcium chlorid.

Solution llo. l: Dissolve sodium chlorid in water until the solutiontests from :3 Bauin to saturation and combine in proper proportions asolution of ammonium chlorid of from 5 Baume saturation adding any ofthe alcove named acids until the desired conductivity and effect on theanode are produced.

Solution No. 5 water to a strengt (heavy hydroinetei is added from 5 pAmmonium chlorid in to satuzation to which er cent. to 100 per cent.

. or the volume or the former, a solution oi" perchlorid of iron ofabout e2 Baum-, or commercial chlorid or" iron of equivalent strength orthe equivalent in dry chlorid of iron; with or without the addition oror the acids mentioned in No. 1.

Solution No. 6: Sodium chlorid in water V from 5 Bauin (heavyhydrometer) to saturation, to which is added from 5 per cent. to 100 percent. of the volume of the former, of a solution of perchlorid of ironof about a O Baurne, or chlorid of iron of equivalent strength, or theequivalent in dry chlorid of iron; with or without the addition of anyof the acids mentioned in No. l.

Solution No. 7 Ammonium chlorid in water to a strength testing from 5Baum heavy hydrorneter) to saturation, to which is added in anyproportion desired a solution of sodium chlorid in water testing from 5Baum {heavy hydrometer) to saturation, and to the combined solutions isadded from 5 per cent. to 100 percent. of the volume of the former.solutions of perchlorid or" iron of about l-12 Baur strength or chloridto strength testing of iron of equivalent streng h, or the equivestingfrom 5 Baum' silent in dry chlorid of iron; with or without the additionof any of the acids mentioned in No. 1.

As illustrations of solutions produced by these formulas, I may note thefollowing: No.1. Calcium chlorid in water to Baum test 20 1 gal.Hydrochloric acid 0. P 1% oz. No.2. Ammonium chlorid in water to Baumtest 20 1 gal. Sulfuric acid 1 oz. No. 3. Sodium chlorid in ,water toBaum test 20 1 gal. Sulfuric acid 1% oz. No.4. Sodium chlorid in watertest 15 'ggal. Ammonium chlorid in water test e gal. Hydrochloric acid 1oz.

In solutions 5, 6 and 7 no acid is used aside from that in the ironperchlorid solution, but when neutral iron chlorid is used, I find it offurther advantage to lastly add to each ofthe solutions 5, 6 and 7 from9 per cent. to 15 per cent. of the total preceding volume, hydrochloricacid C. P., or the equivalent of hydrochloric acid of lesser I strength.Other acids may also be employed as previously indicated.

The addition of perchlorid of iron, dry chlorid of iron or a solution ofchlorid of iron, to certain of the above formulas, is mostly for thepurpose of keeping the oathode plate clean and preventing the formationof sludge thereon or in the electrolyte.

Having thus described the apparatus and composition of the electrolytes,I shall now proceed with the steps in the operation.

The first step consists in producing1 the image on the plate by any ofthe p otographic or transfer methods well known in the graphic arts.

The back of the plate is next coated with an insulating material, whichmay be chose-n from a great variety, such asshellac dissolved inalcohol, a solution of asphaltum and .parafin, or almost any waxoussubstance, to which has been added a resin or asphaltum, or both.

The plate is then connected with the positive wire of a dynamo orbattery and immersed in a suitable electrolyte, constituting the anodeterminal therein. I have found it preferable and shall claim it asoriginal in electrical etching to maintain the plate horizontally in theelectrolyte with the face (the side containing the image) downward, ashereinbefore described.

In line lates or what are known as line portions 0 combination plates,after a certain "depth is attained, which is technically termed (inchemical'etching), the first bite the powder entirely fills the openingand to an extreme degree, would necessarily take the line away entirely,or if only to a slight extent, would interfere with the duplication ofthe plate by electrotypiug or stereotyping. o prevent this side etchingand thinning of the lines afterhaving obtained a certain depth,reinforcing the side so of the lines must be done in four directions,

whether the plate be etched electrically or chemically, and this I musttherefore do in my electrical etching method, although I am able toobtain a greater depth before this becomes necessary than is possible inchemical etching. It may readily be seen that in very small spaces, suchas between lines that are approximately one-fiftieth of an inch apart,

this, receives no further etching after the first etching, so that thedepth of the plate in such fine portions, therefore, depends entirelyupon the first etching. Herein I claim great superiority owing to thefact that my plate is 50 per cent. to per cent. deeper than the oldplates before the necessity for powdering arises. 1

After powdering more or less of a shoulder is produced, hence by gettingmy plate 100 so much deeper in the first etching, the possibility ofshoulders on the sides of the lines near the printing surface isentirely obviated. Shoulders it may be added, increase the difficulty ofprinting any plate.

It will be apparent to those skilled in the art that some sundry changesand modifications may be made in the apparatus, in the method and insuch details as the formulas of the electrolyte, etc. Thus, I may employ11 plates of various metals or substances, to be etched, and I mayemploy divers metals or other substances instead of carbon for thecathode, and in the apparatus mechanicalequivalents subserving the samefunction.

For example adjustable rods engaging the sliding shaft 19 throughelongated eyes or electrical connections to said cathodes; an anode; ananode support extending over the top oi the tank; electrical connectionstosaid support; and means for moving said support and the anodesuspended therefrom during etching with an appreciable period of rest.

2. Apparatus for electrochemical etching comprising in coinoiaation atank or bath to contain an electrolyte; cathodes suspend ed along" andWithin the Walls of th tanlr; electrical connections to said cathodes;an anode; an anode support extending over the top of the tank;electrical connections to said support; a movable carrier for said anodesupport with mechanically driven means for periodically moving the sameso as. to produce corresponding movement of the suspended anode in theelectrolyte during etching with an appreciable period of rest.

3. Apparatus for electrochemical etching comprising in combination atank or bath to contain anelectrolyte; cathodes suspended along andWithin the Walls of the tanlr; electrical connections to said cathodes;an anode support extending over the top of the tank; electricalconnections to said support said cathodes and anodes being soproportioned as to produce a definite line of precipitation; a rciprocating member carrying the anode support with means to more thesaid reciprocating member in the direction of the precipitation andcurrent flow.

d. Apparatus for electrochemical etching comprising in combination atank or bath to contain an. electrolyte; cathodes suspended along andWithin the walls of the tank; electrical connections to said cathodes;an anode support extending over the top of the tank; electricalconnections to said support; each of said cathodes consisting ofsubdivided units arranged to be separately removed and replaced,

5. r. paratus -for electrochemical etching comprising in combination, atank or bath to contain an electrolyte; cathodes suspended along andWithin the Walls of the tank; eled' trical connections to said cathodes;an anode support extending over the top of the tank;

1 electrical connections to said support;

movable carrier for said anode support "with mechanically driven meansfor peiiodically moving the same so as to produce corresponding movementof the suspended anode in the tank and electrolyte contained therein,during etching; and means for 7- ing the periods movement and rest ofsaid movable carrier;

6. Apparatus for electrochemical etching comprising .incomhination; atank or bath to contain an electrolyte; cathodes suspended along andinthe Walls oi the electrical conne cons to said cathodes;

anode support extending overthe top of tank; el ctrical connections tosaid support; a movable carri r for said anode st ort, with mechanicallydriven means for periodically moving the same so as to producecorresponding movement of the suspended anode in the tank and anelectrolyte contained therein during etching; and means for periodicallyvarying the supply of current to anode.

7. Apparatus for electrochemical etchin comprising in combination; atank or loath contain electrolyte; cathodes suspended along and Withinthe Walls of the tank; electrical connections to said cathodes;

anode; in anode support extending over the p 'no an anode supportextending over the top oi: the tank; electrical connections to llectrical connections to said cathodes; an

ill)

said support; a movable carrier for said 1 anode support, withmechanically driven means for periodically moving the same so as toproduce corresponding movement or" the suspended anode in the tank andan electrolyte contained therein during etching; means for periodicallyinterrupting the supply of current to the anode; adjustable means fordetermining the periods of said movement of the carrier and saidinterruption current supply prising port arranged to hold a plate to heetched suspended in the tank and in the electrolyte con nned therein; adriven member; a loose connection between said driven member and thesaid anode support; one or more cathodes in the tanlr immersed in theelectrolyte; and electrical connections to said anode support and saidcathodes; v

10. Apparatus for electrochemical etching comprising in combination, atank or ii h to contain an electrolyte; cathodes suspended along andwithin the walls at the tent; electrical connections to saidcathodes, ananode; an anode support extending from the top of the electricalconnections to a d means for imparting ver- 1 only to the anodesuspended etching.

t/GS for paratus for electrical com-f in combination, a. tank or loathto contain electrolyte; a movable anode supelectrical etching comprisingin combination, a tank or bath to contain an electrolyte; an anodesupport arranged to hold a plate to be etched suspended in the tank andin the electrolyte contained therein, cathodes surrounding a platesuspended in the electrolyte, a bus-bar for said cathodes, a pluralityof separate current leads extending between different points on theanode support and a source of current and a plurality of separatecurrent leads extending between difi'erent points on said cathode busbar and the same source of current,

12. An apparatus for electrical etching to contain an electrolyte; ananode support contained therein, cathodes surrounding and underlying aplate suspended in the electrolyte, a bus-bar for said cathodes, aplurality of separate current leads extending between different pointson the anode support and a source of current and a plurality of separatecurrent leads extending between diflerent points on said cathode bus barand the same source of current.

In testimony whereof I affix my signature.

JOSEPH H. WEEKS. Witnesses:

LAURA BECKER, PHILIP J. KREWET'I.

